The present invention relates to an information processing apparatus, an information processing method, and a program for the same, and more specifically to an information processing apparatus and an information processing method enabling reduction of power consumption and to a program for the same.
In association with the recent tendency for increasingly higher sophistication of portable devices such as a PDA (Personal Digital Assistants) or a mobile telephone, and some of the devices incorporated therein a plurality of sensors including a CCD (Charge Coupled Device), a GPS (Global Positioning System) sensor, a finger print detection sensor and the like.
In the portable devices incorporating therein various types of sensors as described above, it is necessary to supply a power not only to the sensors themselves, and also to a microcomputer sampling signals outputted from the sensors with a battery having a limited capacity. Therefore power saving in each sensor and in the microcomputer is especially demanded.
Consequently, to reduce power consumption in each sensor, there has been proposed the technique for stopping supply of a power to each sensor during a period after the end of previous sampling until start of next sampling.
Further to reduce power consumption consumed by a microcomputer, there has been proposed the technique for setting the microcomputer in the sleep state in which power consumption is low, for instance, by stopping clocking while each signal outputted from each sensor is being sampled.
Patent Document 1 discloses the technique for reducing power consumption in each sensor by providing, separately from a CPU (Central Processing Unit), a standby control circuit for controlling ON/OFF of a power for the sensor and intermittently running the sensor with the standby control circuit. Also there has been disclosed the technique for setting circuits in the CPU other than those for detecting input signals so that power consumption in the CPU can be reduced.
Patent Document 1:
Japanese Patent Laid-Open No. 2000-88605
In a case where sensors are run intermittently, however, in some types of sensors, a normal result of detection cannot be outputted immediately when power supply is started, and thus an erroneous value may be obtained as a result of sampling, which is disadvantageous.
Further when the state of a microcomputer is returned from the sleep state to the normal state, sometimes the state switching can not be executed at a high speed, for instance, because a certain period of time is required until PLL (Phase Lock Loop) of a memory used in the microcomputer is stabilized, which is also disadvantageous.
In addition, when a sensor required executing sampling in a short cycle is used, a load to the microcomputer increases, which naturally results in increase of power consumption in the microcomputer.